Compression operated fuel injector



Apnl 3, 1956 M. M. PALUCH El AL 2,740,663

COMPRESSION OPERATED FUEL INJECTOR Filed April 9, 1952 2 Sheets-Sheet lApril 3, 1955 M. M. PALUCH ET AL ,740,668

COMPRESSION OPERATED FUEL INJECTOR Filed April 9, 1952 2 Sheets-Sheet 2Jnventors r V 0 i )i attorneys United States Patent Ofiice 2,740,668Patented Apr. 3, 1956 COMPRESSION OPERATED FUEL INJECTOR Milton M.Paluch and Conrad A. Teichert, Grand Rapids, Mich., assignors to GeneralMotors Corporation, Dctroit, Micl1., a corporation of DelawareApplication April 9, 1952, Serial No. 281,336 8 Claims. (Cl. 299-1072)This invention relates to unit fuel injector pumps for internalcombustion engines and particularly to such devices of the enginecompression pressure operated type.

The injector pump of the instant invention comprises a novel combinationof interfitting stationary body and cover members having aligned boreswhich slidably receive and guide longitudinally adjacent end portions ofa compression pressure actuated piston whose movement inwardly towardthe cover member by said compression pressure is opposed by acompression spring between the cover and its adjacent end of the piston.Within the piston and carried thereby is a bushing forming a fuelpumping chamber, into which extends a plunger which is rotatablyjournaled in the cover and retained in abutment with the cover by thespring. The bushing is retained endwise within the piston between aclamping nut and a check valve and nozzle assemblage through which fuelis conducted from the pumping chamber and delivered through the head ofthe piston as the piston is driven upwardly in response to increasedengine compression pressure. Surrounding the check valve within thepiston is a cooling chamber, and the cover, body, piston and bushing areprovided with a novel arrangement of connecting passages and groovesthrough which fuel is supplied to both said pumping and cooling chambersfrom an inlet connection in the body, and is circulated through saidcooling chamber and subsequently returned to an outlet connection in thecover. The plunger is rotatably adjusted through a novel form of torsionspring drive mounted on the cover.

It is the principal object of the invention to provide such a unitinjector pump incorporating relatively few major parts which are ofrelatively simple design for economy of manufacture and convenience ofassembly, yet are individually rugged and cooperate in providing anassembly which is trouble free in operation.

These and other objects of the invention will be more clearly understoodfrom the following description of a preferred form of the invention,having reference to the drawings wherein:

Figure l is a longitudinal cross sectional view of a unit fuel injectorpump embodying the invention and shown in assembled relation in anopening provided therefor in an engine cylinder head.

Figure 2 is a fragmentary sectional view taken substantially on line 2-2of Figure 1, showing the fuel inlet and outlet connections to the pump.

Figure 3 is a fragmentary transverse sectional view taken substantiallyon line 3-3 of Figure l, showing further details of the torsion springplunger drive.

Figure 4 is a fragmentary transverse sectional view taken substantiallyon line 4-4 of Figure 1, showing further details of the pump parts andtheir fuel passages.

Referring now to the drawings in detail, in Figure 1 there is indicateda portion of an engine cylinder head 2 having an opening 4 extendingtherethrough in which is fitted the cylindrical body 6 of the fuelinjector pump. The body 6 is generally cylindrical in form, having itslower end 8 terminating flush with the inner surface 10 of the cylinderhead and having an external flange 12 at its upper end overlying thecylinder head around the opening 4, which flange may be secured to thecylinder head by studs 14. The internal surface of the body 6 includes acylindrical bore 16 which extends approximately half the length of thebody 6 from its lower end 8, an enlargement or counterbore 18 above thebore 16 and a second enlargement or counterbore 20 at the upper end ofthe body 6. Between the upper end of the bore 16 and the bottom of thecounterbore 18 is an annular chamber 23 which serves as a dash pot forthe flange 24 of the piston 26, downward movement of the piston bei nginitially limited by compression of fuel in this space. A shoulder 22provided on the wall of the body within this dash pot serves as a finalpositive stop for the piston flange. A shoulder 28 formed between thecounterborcs l8 and 26 serves to support an annular fuel strainer 30. Toinsure a gas tight fit between the body 6 and the cylinder head bore 4the bottom outer wall of the body 6 is provided with a circumferentialrecess 32 in which are a plurality of chevron type packing leaves 34arranged in two stacks with a separating spacer 36 between the stacksand held in place by an annular nut 38 threadedly engaging the body 6.

The piston 26 as shown is generally of cup-shape having an end wall orhead 40 and an integral skirt 42 which slidably fits the bore i6 of thebody 6. Adjacent the head 40 the piston skirt is provided with a seriesof external grooves carrying outwardly expanding rings 44, and abovethese rings is an external groove 46 for receiving any gases leakingpast the rings from the engine combustion chamber. Spaced a distanceabove the groove 46 is the aforesaid flange 24 which is formed integralwith the skirt and serves to limit downward movement of the pistonthrough its seating engagement with the shoulder 22 of the body 6. Thepiston skirt 42 extends above the shoulder 24 and preferably has thesame outside diameter as below the shoulder.

A cover member St] has a flange portion 52 overlying and secured to thebody flange 12 by cap screws 54, and :1 depending skirt having a bore 56slidably receiving the upper end of the piston and constituting anextension of the bore 16 of the body 6. The upper portion 58 of thisskirt has an external diameter closely fitting the counterbore 20 of thebody 6 and is preferably sealed thereto against fluid leakage as by theO-ring packing 60. The lower portion 62 of this skirt is of reducedthickness and extends into the counterbore 18 of the body, there being aclearance space 64 for passage of fuel therebetween from the strainer30. The lower end of the skirt portion 62 has a counterbore 66 forming adash pot into which the flange 24 on the piston is received as thepiston is driven upwardly by the engine compression and combustion gaspressures. The external shoulder 68 between the skirt portions 58 and 62serves to retain the strainer 30 seated against the shoulder 28 of thebody.

The strainer 30 is preferably selected to have an external diameterfitting the diameter of the counterbore 20 of the body, and opposite thestrainer this counterbore 20 is provided with an internal groove 70serving as a fuel receiving chamber. A fuel inlet connection indicatedgenerally at 72 (Figure 2) is made at one side of the body flange l2,and a drilled passage 74 extends transversely through this flange fromthe connection 72 to the fuel receiving chamber 70.

Extending through the cover skirt portion 62 between the shoulders 28and 68 is a downwardly inclined fuel passage 76 which connects at itsinner and lower end with a vertically extending external recess 78formed in the outer wall of the piston skirt 42 and of sufiicient lengthto maintain communication with passage 76 throughout the piston stroke.A second downwardly inclined fuel passage extends through the pistonskirt wall from the lower end of this recess 78.

The head 40 of the piston is provided with an opening 91) whichterminates at its upper end in a counterbore 92. Seated on the bottom ofthe counterbore 92 and extending through the opening is a fuel nozzle 94having a longitudinal fuel delivery passage 96 terminating at its lowerend in a plurality of radiating smaller fuel spray passages 98. At theupper end of the nozzle passage 96 is an enlargement or entrance chamber100 in which is positioned a flat disc valve 102. Bushing the nozzle 94within the countcrbore 92 is a sleeve 104 which extends above the upperend of the nozzle. Seated in end-to-end stacked relation upon the nozzle94 and within the sleeve 104 are a valve seat 106 having a longitudinalpassage 108 communicating with the chamber 100, a check valve body 110and a spacer 112. Only the reduced diameter lower end portion of thespacer 112 is received within the sleeve 104,

and this sleeve has a free floating fit in the longitudinal directionbetween the spacer and the bottom of the counterbore 92 in the piston.The lower end face of the check valve body 110 is made concave as shownat 114 and slidably mounted centrally of this body is a cupshaped checkvalve 116 whose lower end normally rests on the seat 186 and closes thepassage 108. Normally retaining the check valve thus seated is acompression spring 118 whose upper end seats in a well 120 formed in thebottom of the spacer 112, and whose lower end is retained by a flange122 on a guide pin 124 the opposite 1 ends of which extend into the well120 and into the interior of the cup-shaped check valve 116. Two or morepassages 126 extend longitudinally through the spacer 112 andcommunicate with similar passages in the check valve body for conductingfuel to the concavity 114. To insure communication between thesepassages 125 and 126, the abutting faces of the spacer and check valvebody are relieved by annular oppositely facing grooves connecting theirrespective passages 125 and 126. The spacer 112 is also preferablyprovided with a small radial passage (not shown) extending to the outerperiphery thereof from the well 120 for the purpose of relieving thiswell of any pressure build up of fuel leaking into the well past thecheck valve from the concavity 114.

The upper end of the spacer 112 is abutted by the lower end of a bushing128 having a close fit with the internal wall 130 of the piston skirt42. An externally threaded nut 132 screwed into the upper end of thepiston skirt serves to clamp the bushing 128, spacer 112, check valvebody 110, check valve seat 106 and nozzle 94, all downwardly against thepiston end wall 40. As shown, between the nut 132 and the upper end ofthe bushing 128 is a washer whose upper face is provided with a smalldepression to receive the lower end of a set screw which locks the nutagainst rotation relative to the washer, and the washer in turn islocked against rotation relative to the bushing by providing the Washerwith a depending tab which engages a slot in the upper end of thebushing. The interior of the bushing 128 forms a fuel pumping chamber134 and extending thereinto through the upper end of the bushing is aplunger 136 having an enlarged upper end 138 loosely piloted in acounterbore 140 formed in the cover 50. A plunger retainer washer 142 isretained in abutment with the end wall 144 of this cover by the upperend of a coil compression spring 146 whose lower end seats on a washer148 which in turn seats in the bottom of a counterbore 150 formed in theupper end of the piston skirt 42. The spring 146 thereby serves both toretain the plunger 136 fixed against longitudinal movement with thepiston and bushing, and also biases the piston and its associated partsoutwardly of the cover 50 and body 6 to normally retain the pistonflange 24 in abutment with the body shoulder 22. To prevent the plungerfrom dropping downwardly in the bushing and interfering withreciprocation of the piston in the event of breakage Cit of the spring146, a safety bolt 147 is provided which extends transversely into thecover member 50 and terminates below the plunger retainer washer 142.The bushing 128 is provided with an annular external groove 152 whoseupper end is connected with the passage 80 in the piston skirt by a slot154. Two diametrically opposite assages 156 and 158 extend transverselythrough the bushing from the lower end of the annular groove 152. Liningthe internal wall of the piston skirt opposite the passages 156 and 158and extending to the upper end of the groove 152 is a wear-resistantsleeve 159 which is retained against longitudinal displacement byshoulders formed in the bushing and piston, as shown.

The plunger 136 is provided with an external relief groove 160 andconnecting transverse passages 162 and 164 which intersect alongitudinal passage 166. The transverse passages 162 and 164 and theaxial passage 166 maintain the upper and lower ends of the groove 160 inconstant communication with the fuel pumping chamber 134 below thebottom end of the plunger 136. A land 168 is provided in the groove 160to control the opening and closing of the ports 156 and 158 in thebushing in timed relation to the reciprocation of the piston 26. Thisland 168 has circumferentially extending upper and lower edges 170 and172 terminating at one end in a continuous longitudinally extending edge174 and at the other end in connecting helical, circumferential andlongitudinal edges 176, 178 and 180, respectively. In the relativepositions of the ports as shown, the piston is at the bottom of its fuelfilling stroke and the plunger groove 160 is open to both ports 156 and158 in the bushing, permitting fuel from the annular groove 152 to flowto the pumping chamber 134 through the plunger passages 162, 164 and166. Upon upward movement of the piston, providing the angular positionof plunger relative to the bushing 128 remains as shown, the bushingports 156 and 158 are closed simultaneously as they move past the lowercircumferential edge 172 of the land 168, and the fuel trapped in thepumping chamber is subjected to pressure. With continued upward movementof the piston, the bushing ports are again opened to the plunger groove160 as they pass over the upper circumferential edge 170 of the land168, thereby relieving the fuel pressure in the pumping chamber. In itsangular position shown, the plunger is set to effect the maximum fuelinjection quantity per piston operating cycle. A decrease in the amountof fuel injected per cycle, accompanied by a delay in start ofinjection, is obtained by rotating the plunger in the direction(clockwise as viewed in Figures 3 and 4) to bring the helical edge 176opposite the bushing port 156 so that the closing of this port 156occurs later in the upward stroke of the piston. With the plungerfurther rotated far enough to bring the short circumferential edge 178opposite the bushing port 156, a pilot or idling injection rate isobtained, and a still further rotation of the plunger to bring the spacebetween the longitudinal edges 180 and 174 opposite the port 156 resultsin a complete stoppage of injection.

The upper end 138 of the plunger 136 is provided with end splines orteeth extending into the counterbore 140 in the cover 50. A plungerrotator in the form of a shaft 192 is journaled in the upwardlyextending boss 1.94 of the cover 50, and the lower end of this shaft hasan external flange 196 rotatably seated by the end wall of thecounterbore 140 and provided with depending end splines or teeth, one ofwhich is shown at 198 in Figure 2. An annular plate 200 whose perimeteris suitably notched to receive these teeth serves to rotatively couplethe plunger and plunger rotator together. The teeth 196 on the plungerand 198 on the rotator, as well as the plate 200, have sufiicient radialclearance in the counterbore 140 to accommodate slight misalignment ofthe plunger and thereby prevent any tendency of the plunger to bind inthe bushing 128. Journaled on the cover boss 194 for rotation coaxiallyof the rotator shaft 192 is a doublearmed lever 202 having an annularhub 203 of upwardly presenting U-shape in radial section which is closedby a cover plate 204. Within the hub 203 and journaled axially adjacenteach other on the inner wall of this hub are upper and lower lug members206 and 208 having radially extending and vertically overlappingprojections 210 and 212, respectively. Driven and driving pins 214 and216, respectively, which are carried by the hub cover plate 204 and thebottom wall of the hub 203, extend between the overlapping faces of theprojections 210 and 212. A torsionally pre-stressed helical spring 218,which surrounds these parts within the hub 203, has its opposite endshooked to the projections 210 and 212 (Figure 3) and tends to maintainthe pins 214 and 216 in alignment with each other, whereby eitherclockwise or counterclockwise rotation of the driving pin 216 with thelever 202 about the cover boss 194 is transmitted to one of the lugmembers and by it through the spring to the other lug member and thenceto the driven pin 214. A stop pin 220 fixed in the cover 50 serves toengage the lower end of the driving pin 216 and thereby limit rotationof the lever beyond the full fuel position in which the lever is shown,and a second stop pin similarly limits lever movement in the oppositedirection beyond the fuel otf position. A dog 222, keyed to the upperend of the plunger rotator 192 above the cover 50, has a bifurcated end223 embracing the pin 214. Angular adjustment of the plunger rotatorabout its axis relative to the lever 202 may be provided for by makingthe bifurcation in the lever substantially wider than the diameter ofthe pin and locating the pin laterally therewithin between opposing setscrews (not shown) threaded in the opposite arms of the bifurcation.

Between the lower end of the bushing 128 and the head end 40 of thepiston 26 is an annular chamber 238 which surrounds the spacer 112 andsleeve 104 housing the check valve parts. A flat on the cylindricalouter surface of the bushing 128 provides a passage 232 to this chamberfrom the annular groove 152. A blind transverse passage 234 (Figure 2)extending outwardly from a recess 236 in the lower end of the bushingprovides a fuel return and a connecting longitudinal passage 237 isprovided in the wall of the piston skirt from the chamber 230 to theinterior of the cover 50, above the piston, from which a transversepassage 238 in the cover conducts the fuel to an external return line240.

The excess fuel not required for injection is thus forced to circulatethrough the annular chamber 230 in the piston during its return to thetransfer pump or other source of supply (not shown), and in so doingserves to cool the piston ring section of the piston and the check valveparts.

A second longitudinal passage 242 extends through the wall of the pistonskirt 42 and connects the external groove 46 on the piston skirt to theinterior of the cover above the piston, thereby insuring that air andcombustion gases leaking past the piston rings will be carried into thefuel being returned to the source, rather than pass into thecounterbores 18 and 20 of the body where they would aerate the incomingfuel and render the hydraulic stop action of the piston flange 24 anddash pots 23 and 66 ineffective. Also, any leakage of fuel downwardly ofthe bore 16 from the dash pot 23 will be collected by the groove 46 andconducted out via the passage 242 in the same manner.

Angular alignment of the bushing 42 with the piston 26 and of the pistonwith the cover 50 is effected by the dowels 250 and 252. Dowel 250 isfixed in the piston skirt and has its inner end received in alongitudinal slot 254 milled in the lower outer side of the bushing, andthe dowel 252 is fixed in cover skirt portion 62 and has its inner endslidably received in a longitudinal slot 256 milled in the upper outerside of the piston skirt. The slot 256 is of suflicient length toaccommodate the reciprocation of the piston in the cover bore 56.

We claim:

1. In an engine compression pressure operated fuel pump and injectorunit, a piston, stationary body and cover members in nesting relationhaving aligned bores slidably supporting longitudinally adjacentsections of the piston, said cover member having a fuel outletconnection, said body member having a fuel inlet connection, and meansforming a fuel pumping chamber within the piston, said body and covermembers having oppositely facing annular grooves forming a fuelreceiving chamber in communicat 150.1 with said inlet, said cover memberand piston having connecting passages leading from said receivingchamber to said pumping chamber.

2. in an engine compression pressure operated fuel pump and injectorunit, a piston, a stationary body forming a bore for said piston, acover secured to said body and forming an extension of said bore, saidpiston having separate internal fuel pumping and cooling chambers, afuel inlet and a fuel outlet, said body, cover and piston being providedwith communicating passages connecting said inlet to both said chambers,said piston and cover being provided with other communicating passagesconnecting said cooling chamber to said outlet.

3. In an engine compression pressure operated fuel pump and injectorunit, a stationary body adapted to fit an opening in an engine cylinderhead, said body having a core extend titcrcthrough and having anexternal mounting flange z. its upper end, said bore having a lowerpiston guiding portion and an enlarged upper portion forming a shoulderat the upper end of said guiding portion, a piston slidably fitting saidbore lower portion and having an external flange intermediate its ends,a cover for said body having a depending skirt portion slidablyreceiving the piston tithin said enlarged bore portion and a flangeseating on said body flange, said piston having an internal fuel pumpingchamber, a plunger extending into said chamber itavi a flange abuttingsaid cover, a washer enclosing said plunger flange and abutting saidcover, and a compression spring seating at its opposite ends againstsaid washer and the upper end of the piston and normally holding said 21flange in abutment with said body shoulder. in an engine compressionpressure operated fuel pump and injector unit, a piston having anexternal flange encircling its side wall intermediate the ends of thepiston, :2 stationary body having a bore extending therethrough in whichsaid piston is reciprocable, said bore having a lower portion closelyfitting the piston side wall below said flange and terminating at itsupper end in an upwardly open dash pot for receiving said flange, acover secured to the upper end of said body and having a sleeve portionextending into said enlarged bore portion, said sleeve having a closefit with the piston side wall above said flange and terminating at itslower end in a downwardly open dash pot for receiving said flange.

5. in an engine compression pressure operated fuel pump and injectorunit, a cup-shaped piston having an aperture in its end wall, a fuelnozzle seated on the piston end wall and extending outwardly of thepiston through said aperture, check valve means seated on said nozzleand spaced inwardly from the side walls of the piston to form a coolingchamber, a bushing closely fitting the internal side walls of the pistonabove said check valve means and seating at its lower end on said checkvalve means, said bushing being provided with a longitudinal groove openat its lower end to said cooling chamber, the interior of said bushingforming a fuel pumping chamber having communication with the nozzlethrough said check valve means, a stem slidably received by said bushingand forming a plunger in said pumping chamber, a nut threadedly engagingthe piston side wall above the bushing and in clamping engagement withthe upper end of the bushing, a stationary body having a bore slidablyreceiving the piston, a cover secured to the upper end of said body, anda compression spring interposed between said cover and the upper. end ofthe piston, said body, piston and bushing having interconnectingpassages for delivery of fuel to said pumping chamber and to the upperend of said groove, and said piston and cover having other passages forreturning fuel from said cooling chamber.

6. In a unit fuel injector pump for automatically delivering meteredquantities of fuel to an internal combustion engine cylinder in timedrelation to changes in engine combustion chamber pressure, a pistonhaving a head and an integral hollow skirt, said head having a centralopening, a fuel nozzle extending through said opening from within thepiston and seated by said head, check valve means within the pistonincluding a valve seat, a valve body and a spacer in aligned, stacked,endto-end abutment with said nozzle, said valve seat and nozzle havingaligned fuel delivery passages, a valve slidably mounted in the valvebody for reciprocation longitudinally of the piston, and a spring seatedin said spacer biasing the valve against said seat, a bushing closelyfitting the internal walls of the piston skirt and having its inner endin endwise abutment with said spacer, a centrally apertured nutthreadedly received in the outer end of the piston skirt and in clampingabutment with the outer end of the bushing, said spacer and valve bodyhaving aligned fuel passages extending therethrough longitudinally ofthe piston and communicating with the interior of the bushing, saidvalve body having its end opposite the valve seat relieved to providecommunication between said last named fuel passages and the lowersurfaces of said valve, a pump plunger extending into the upper end ofsaid bushing, means including connecting passageways provided in thewalls of said piston skirt and bushing for introducing fuel to theinterior of the bushing below said plunger, and means slidably guidingsaid piston and supporting said plunger against movement longitudinallyof the piston whereby during upward movement of the piston the fuelbelow the plunger will be forced past said check valve for deliverythrough said nozzle.

7. In a unit fuel injector pump, a stationary member, reciprocablepiston means slidably received within said member and forming a fuelpressure chamber, a plunger member extending into said chamber andjournaled by said stationary member, a compression spring biasing thepiston means outwardly of said stationary member and retaining saidplunger member in abutment with said stationary member, a leverjournaled on said stationary member coaxially of said plunger member,and a torsion spring yieldably opposing relative rotation in eachdirection between said plunger member and lever.

8. in a unit fuel injector pump, a stationary member, reeiprocablepiston means slidably received within said member and forming a fuelpressure chamber, a plunger member extending into said chamber andjournaled' by said stationary member, a compression spring biasing thepiston means outwardly of said stationary member and retaining saidplunger member in abutment with said stationary member, a leverjournaled on said stationary member coaxially of said plunger member, adriving pin fixed to the lever and a driven pin fixed to the plungermember, a pair of lug members journaled on the lever having portionsengageable with the respective opposite sides of said pins, and atorsion spring urging said portions toward each other for yieldablytransmitting rotational movements of the lever to said plunger member.

References Cited in the file of this patent UNITED STATES PATENTS2,203,057 Moore June 4, i940 2,552,777 French May 15, 1951 2,576,451Dickson Nov. 27, 1951 2,656,178 Hughes Oct. 20, 1953 FOREIGN PATENTS360,076 Great Britain Nov. 5, 1931

